Motor

ABSTRACT

A motor includes a rotor with one or more magnets, a rotor core holding the one or more magnets, a spacer that contacts the one or more magnets, and a rotor holder. The rotor holder includes a holder lid portion and a holder tubular portion in a tubular shape extending to one side in the axial direction from a radially outer edge of the holder lid portion. The holder lid portion includes a holder first surface that extends radially inward from an inner surface of the holder tubular portion, a holder second surface that extends radially and is radially inward of the holder first surface and on the other side in the axial direction, and a connecting surface connecting the holder first surface and the holder second surface.

CROSS REFERENCE TO RELATED APPLICATION

The present invention claims priority under 35 U.S.C. § 119 to JapaneseApplication No. 2019-141621 filed on Jul. 31, 2019 the entire contentsof which are hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present disclosure relates to a motor.

BACKGROUND

In a conventional motor, for example, a frame, a rotor core, and amagnet are integrally formed by resin molding to form a rotor.

The rotor having the above structure may cause deterioration inpositioning accuracy of the rotor core and the magnet with respect tothe frame depending on the amount of resin, deformation during curing,and the like. The rotor also has a structure in which the frame, therotor core, and the magnet are integrated with resin, so that it isdifficult to increase strength of the rotor.

SUMMARY

A motor according to an example embodiment of the present disclosureincludes a rotor rotatable about a center axis and a stator radiallyfacing the rotor. The rotor includes one or more magnets, a rotor coreholding the one or more magnets, a spacer that is in contact with atleast the one or more magnets in an axial direction, and a rotor holderthat houses the one or more magnets, the rotor core, and the spacerinside the rotor holder. The rotor holder includes a holder lid portionthat extends in a radial direction, and a holder tubular portion in atubular shape extending to one side in the axial direction from aradially outer edge of the holder lid portion. The holder lid portionincludes a holder first surface that extends radially inward from aninner surface of the holder tubular portion, a holder second surfacethat extends radially and is radially inward of the holder first surfaceand on another side in the axial direction, and a connecting surfaceconnecting a radially inner end of the holder first surface and aradially outer end of the holder second surface. The spacer includes aspacer first surface in contact with the holder first surface, and aspacer second surface in contact with at least a portion of each of theone or more magnets.

The above and other elements, features, steps, characteristics andadvantages of the present disclosure will become more apparent from thefollowing detailed description of the example embodiments with referenceto the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view of a motor according to anexample embodiment of the present disclosure.

FIG. 2 is a view of a rotor and a stator of the motor illustrated inFIG. 1 as viewed from below in an axial direction.

FIG. 3 is an enlarged longitudinal sectional view of a rotor and astator of a motor according to an example embodiment of the presentdisclosure.

FIG. 4 is an enlarged sectional view of a fixed portion of a circuitboard according to an example embodiment of the present disclosure.

FIG. 5 is an exploded perspective view of a rotor according to anexample embodiment of the present disclosure as viewed from below in theaxial direction.

FIG. 6 is an enlarged sectional view of a fixed portion of a circuitboard in a motor of a first modification of an example embodiment of thepresent disclosure.

FIG. 7 is an enlarged sectional view of a fixed portion of a circuitboard in a motor of a second modification of an example embodiment ofthe present disclosure.

FIG. 8 is an enlarged sectional view of a rotor and a stator of a motorof a third modification of an example embodiment of the presentdisclosure.

FIG. 9 is a plan view of a spacer of a fourth modification of an exampleembodiment of the present disclosure.

FIG. 10 is a view of a rotor and a stator of a motor of a fifthmodification of an example embodiment of the present disclosure asviewed from below in the axial direction.

FIG. 11 is an enlarged longitudinal sectional view of a rotor and astator of a motor according to an example embodiment of the presentdisclosure.

FIG. 12 is an exploded perspective view of a rotor according to anexample embodiment of the present disclosure as viewed from below in theaxial direction.

FIG. 13 is a perspective view illustrating an example of a ceiling fanusing a motor according to an example embodiment of the presentdisclosure.

DETAILED DESCRIPTION

Hereinafter, example embodiments of the present disclosure will bedescribed in detail with reference to the drawings. In the presentspecification, a direction parallel to a center axis Cx of a shaftextending vertically is indicated as an “axial direction”. A directionorthogonal to the center axis Cx is indicated as a “radial direction”.In addition, a direction along an arc about the center axis Cx isindicated as a “circumferential direction”. Above and below a motor 100are defined with reference to the motor 100 illustrated in FIG. 1. Thename of each direction described above is used for the sake ofexplanation, and does not limit a positional relationship and adirection of the motor 100 when in use.

FIG. 1 is a longitudinal sectional view of the motor 100 according tothe present disclosure. FIG. 2 is a view of a rotor 1 and a stator 2 ofthe motor 100 illustrated in FIG. 1 as viewed from below in the axialdirection. FIG. 3 is an enlarged longitudinal sectional view of therotor 1 and the stator 2 of the motor 100. FIG. 2 does not illustrate abracket 4 and a frame 5.

As illustrated in FIGS. 1 to 3, the motor 100 includes the rotor 1, thestator 2, a shaft 3, the bracket 4, the frame 5, a bearing 6, a circuitboard 7, and a first fixing member 8. The stator 2 is held by thebracket 4. The rotor 1 extends along the center axis Cx, and isrotatably supported by the shaft 3 fixed to the bracket 4 via thebearing 6. The rotor 1 has an inner surface facing an outer surface ofthe stator 2 in the radial direction. That is, the motor 100 is abrushless DC motor of an outer rotor type. Hereinafter, details of eachpart of the motor 100 will be described with reference to the drawings.

As illustrated in FIG. 1, the bracket 4 and the frame 5 are disposedbelow in the motor 100 in the axial direction to cover the rotor 1 andthe stator 2 from below in the axial direction. The bracket 4 isdisposed at a lower end of the motor 100 in the axial direction in acentral portion in the radial direction. The bracket 4 has the centeraligned with the center axis Cx. The bracket 4 includes a shaft holdingportion 41, a stator holding portion 42, and a frame holding portion 43.

The shaft holding portion 41 is disposed in a central portion of thebracket 4 in the radial direction. The shaft holding portion 41 is athrough-hole into which the shaft 3 is inserted. The shaft 3 is insertedinto the shaft holding portion 41 and is fixed. Although examples of amethod for fixing the shaft 3 include press-fitting, the presentdisclosure is not limited thereto. For example, welding, adhesion,bonding, and the like may be available. When the bracket 4 is a resinmolding, the shaft holding portion 41 may be integrally molded by insertmolding.

The shaft 3 may pass through the shaft holding portion 41. Specifically,an axially lower end portion of the shaft 3 may be positioned axiallybelow an axial end portion of the shaft holding portion 41. The shaftholding portion 41 may have a portion (an axially lower end portion inFIG. 2) into which the shaft 3 is not inserted. The shaft holdingportion 41 is provided at its bottom with a tabular shaft lid portion44. When coming into contact with the shaft 3, the shaft lid portion 44can axially position the shaft 3. When the shaft lid portion 44 isattached, contamination of foreign materials into the shaft holdingportion 41 can be reduced and the shaft 3 can be prevented from beingexposed outside. Although the bracket 4 of the present exampleembodiment has a structure in which the shaft lid portion 44 is attachedto a recessed portion having an inner diameter larger than that of theshaft holding portion 41, the present disclosure is not limited to thestructure. For example, the shaft lid portion 44 may be configured to beat least partly disposed inside the shaft holding portion 41.

The stator holding portion 42 has a tubular shape projecting axiallyupward from a radially outer edge of the bracket 4. The stator holdingportion 42 has a radially inner surface facing an outer surface of theshaft 3 at an interval. The shaft and the stator holding portion 42 havea radial interval therebetween in which a rotor hub 11, described below,of the rotor is partly disposed. Then, the rotor hub 11 is rotatablysupported by the shaft 3 using the bearing 6. Details of the rotor hub11 and the bearing 6 will be described below.

The frame holding portion 43 is provided on an outer surface of thebracket 4. The frame 5 is fixed to the bracket 4 while being in contactwith the frame holding portion 43. Here, the frame 5 will be described.The frame 5 includes a frame planar portion 50, a frame tubular portion51, and a frame protruding portion 52.

The frame planar portion 50 has a plate-like shape extending in adirection orthogonal to the center axis Cx. The frame planar portion 50has an annular shape provided in its radially central portion with theframe tubular portion 51.

The frame tubular portion 51 has a tubular shape extending axiallyupward. The inner surface of the frame tubular portion 51 is in contactwith the frame holding portion 43. This causes the frame 5 to be fixedto the bracket 4. Although examples of a method for fixing the frameholding portion 43 to the frame tubular portion 51 includepress-fitting, the method is not limited to press-fitting. For example,they may be fixed to each other by a method such as welding or bonding.

The frame protruding portion 52 has a tubular shape extending axiallyupward from a radially outer edge of the frame planar portion 50.Providing the frame protruding portion 52 enables increasing rigidity ofthe frame 5. The frame protruding portion 52 can enclose the peripheryof the circuit board 7, and also can protect the circuit board 7.Specifically, this enables reducing contamination of foreign substanceinto the circuit board 7 from outside the motor 100.

Next, the stator 2 will be described. The stator 2 radially faces therotor 1. The stator 2 generates magnetic flux in accordance with drivingcurrent. As illustrated in FIGS. 2 and 3, the stator 2 includes a statorcore 21, an insulator 22, and a coil 23.

The stator core 21 is a magnetic body. For example, the stator core 21is formed by layering electromagnetic steel plates in the axialdirection. The stator core 21 includes the core back portion 211 in atubular shape extending along the center axis Cx, and the plurality ofteeth 212. As illustrated in FIG. 2, the core back portion 211 includesa first annular portion 213, a second annular portion 214, a support rib215, and a through-hole 216.

The first annular portion 213 has an annular shape with the centeraligned with the center axis Cx. The second annular portion 214 isdisposed radially inward of the first annular portion 213 at aninterval. As with the first annular portion 213, the second annularportion 214 also has the center aligned with the center axis Cx. Aplurality of support ribs 215 connects the first annular portion 213 andthe second annular portion 214 in the radial direction.

The through-hole 216 is formed at the center of the second annularportion 214 in a plane orthogonal to the center axis Cx. Into thethrough-hole 216, the stator holding portion 42 of the bracket 4 isinserted. The stator holding portion 42 has an outer surface that comesinto contact with an inner surface of the second annular portion 214.This causes the core back portion 211 to be fixed to the bracket 4.

The second annular portion 214 and the stator holding portion 42 arefixed to each other by press-fitting, for example. However, fixingbetween the second annular portion 214 and the stator holding portion 42is not limited to press-fitting, and methods enabling firm fixingbetween the second annular portion 214 and the stator holding portion42, such as bonding and welding, can be widely used. The stator 2 hasthe center aligned with the center axis Cx.

The teeth 212 extend radially outward from an outer surface of the firstannular portion 213 of the core back portion 211. The core back portion211 includes the first annular portion 213 and the second annularportion 214, so that stress to act on the second annular portion 214 tofix the second annular portion 214 to the stator holding portion 42 isless likely to act on the first annular portion 213. This enablesreducing displacement of the teeth 212 and deformation of the teeth 212due to stress at the time of fixing the core back portion 211.

The support rib 215 of the stator core 21 is formed with a fixing memberinsertion portion 217 extending in the axial direction (refer to FIG.3). The fixing member insertion portion 217 extends axially upward froma lower surface of the stator core 21. The fixing member insertionportion 217 may be a hole portion in a recessed shape with an axiallyupper end closed, or may be a through-hole passing through in the axialdirection. Into the fixing member insertion portion 217, a stator fixedportion 81, described below, of the first fixing member 8 is inserted.

As illustrated in FIG. 2, the circuit board 7 is formed in an arch-likeshape. Specifically, the shape is acquired by cutting an annular flatplate in a circumferential direction within a predetermined center anglerange, and has an outer peripheral surface in an arc-like shape asviewed in the axial direction. The circuit board 7 is fixed to thestator core 21 at two places that are opposite ends in thecircumferential direction with respective first fixing members 8. Thecircuit board 7 is fixed at its opposite ends in the circumferentialdirection to the stator core 21 with the respective first fixing members8. That is, two fixing member insertion portions 217 are each disposedin a different support rib 215 of the core back portion 211. The fixingmember insertion portion 217 is provided at a position aligned with aboard through-hole 73 of the circuit board 7 in the axial direction whenthe circuit board 7 is disposed in an attaching position in the statorcore 21 (refer to FIG. 3). When the circuit board 7 is configured to befixed at its opposite ends in the circumferential direction, the firstfixing members 8 can be disposed at a wide interval. This enables thecircuit board 7 to be stably fixed.

The insulator 22 is disposed enclosing a part of the core back portion211 of the stator core 21 and at least partly the teeth 212. Theinsulator 22 is, for example, formed of resin having insulatingproperties. The insulator 22 includes an insulator protruding portion221 provided at a radially outer end of the teeth 212 while extending inthe axial direction. The insulator protruding portion 221 is a guideused when a conducting wire of the coil 23 is wound. The insulator 22 isalso provided in its radially inside portion with a wall portionextending in the axial direction as with the insulator protrudingportion 221. The insulator protruding portion 221 also serves as aholding portion for holding the circuit board 7.

The coil 23 is formed by winding a conducting wire around the teeth 212enclosed by the insulator 22. The coil 23 is insulated from the teeth212 by the insulator 22. The coil 23 is excited by supplying electriccurrent to the conducting wire. The motor 100 rotates the rotor 1 usingattraction and repulsion between the coil 23 and a magnet 14.

The circuit board 7 is disposed below the motor 100 in the axialdirection. Specifically, the circuit board 7 is disposed at a positionfacing an axially lower surface of each of the rotor 1 and the stator 2in the axial direction. The circuit board 7 is mounted with a circuitfor supplying electric power (electric current) to the coil 23. Examplesof a circuit for supplying electric power include an inverter circuit, acontrol circuit, and the like. The circuit board 7 may be mounted with apower source circuit. As illustrated in FIG. 2, the circuit board 7 hasan arch-like shape extending in the circumferential direction as viewedin the axial direction. However, the circuit board 7 is not limitedthereto, and may be in a shape such as a rectangle. Circuit boards eachhaving a shape extending in the circumferential direction can be widelyused. The circuit board 7 may be in an annular shape having a centralportion provided with a through-hole, and may be disposed enclosing aradially outer portion of the bracket 4.

As illustrated in FIG. 4, the circuit board 7 includes a first wiringpattern 71, a second wiring pattern 72, and the board through-hole 73.The first wiring pattern 71 is formed on an upper surface of the circuitboard 7 in the axial direction, i.e., on a surface axially facing thelower surface of each of the rotor 1 and the stator 2 in the axialdirection. The second wiring pattern 72 is formed on a lower surface ofthe circuit board 7 in the axial direction, i.e., on a surface oppositeto the surface facing the rotor 1 and the stator 2. In the presentexample embodiment, the illustrated first wiring pattern 71 and secondwiring pattern 72 are identical in potential.

The board through-hole 73 passes through the circuit board 7 in theaxial direction. In the present example embodiment, the boardthrough-hole 73 is formed inside the circuit board 7, and has ahole-like shape closed in the circumferential direction. However, theboard through-hole 73 is not limited thereto, and may be formed in aperipheral portion of the circuit board 7, having a shape with anopening formed in a part of an outer peripheral portion of the boardthrough-hole 73, e.g., a cut-out shape. Through the board through-hole73, at least a part of a board holding portion 82, described below, ofthe first fixing member 8 passes vertically.

Then, as illustrated in FIG. 1, the circuit board 7 has the uppersurface mounted with a position detection element 74. The positiondetection element 74 is, for example, a hall element that detectsfluctuations of magnetic force of the magnet 14, described below, of therotor 1 rotating to detect a rotational position of the rotor 1. Theposition detection element 74 is disposed below the magnet 14 in theaxial direction. The rotor 1 may be separately provided with a componentfor position detection so that a position of the component for positiondetection is detected by the position detection element 74.

The circuit board 7 is fixed to the stator core 21 with the first fixingmember 8. Next, details of the first fixing member 8 will be describedwith reference to additional drawings. FIG. 4 is an enlarged sectionalview of a fixed portion of the circuit board 7. The first fixing member8 is made of material having conductivity, such as stainless steel,aluminum, or aluminum alloy. As illustrated in FIGS. 3 and 4, the firstfixing member 8 includes the stator fixed portion 81 and the boardholding portion 82.

The board holding portion 82 includes a large-diameter portion 821 and aleg portion 820. The large-diameter portion 821 has a cylindricalcolumnar shape extending in the axial direction. The large-diameterportion 821 has an outside diameter larger than an inner diameter of theboard through-hole 73.

The leg portion 820 extends downward in the axial direction from a lowersurface 824 of the large-diameter portion 821. The leg portion 820includes a small-diameter portion 822 and a caulked portion 823. Thesmall-diameter portion 822 has a cylindrical shape. The small-diameterportion 822 has an outside diameter smaller than the outside diameter ofthe large-diameter portion 821. The small-diameter portion 822 extendsdownward in the axial direction from the lower surface 824 of thelarge-diameter portion 821.

The leg portion 820 is inserted into the board through-hole 73 from anupper surface side of the circuit board 7. The leg portion 820 has alower end portion projecting from the lower surface of the circuit board7 that is folded (caulked) radially outward to form the caulked portion823. At this time, the caulked portion 823 comes into contact with thesecond wiring pattern.

Although in the present example embodiment, the caulked portion 823indicates a shape after a caulking process is applied, the caulkedportion 823 is not limited thereto. The portion including a state beforethe caulking process is applied may be referred to as the caulkedportion 823. To facilitate the caulking process, the caulked portion 823may be reduced in thickness to less than the small-diameter portion 822,or a boundary portion between the small-diameter portion 822 and thecaulked portion 823 may be processed such that a groove is formed, forexample.

The large-diameter portion 821 has an annular shape in a portionradially outside the small-diameter portion 822 in the lower surface824. The large-diameter portion 821 is not limited to a cylindricalcolumnar shape as long as the large-diameter portion 821 has aprojection plane in the axial direction having an outer edge positionedradially outside an outer edge of a projection plane of thesmall-diameter portion 822. For example, a column-like shape or atubular shape, having a polygonal cross section, may be available. Whenthe first fixing member 8 is attached to the stator core 21, the lowersurface 824 is disposed flush with a lower surface of the insulatorprotruding portion 221 and the stator core 21.

The stator fixed portion 81 has a cylindrical columnar shape extendingaxially upward from an upper surface 825 of the large-diameter portion821 of the board holding portion 82. The stator fixed portion 81 has anoutside diameter smaller than the outside diameter of the large-diameterportion 821. This causes the large-diameter portion 821 to have anannular portion radially outside the stator fixed portion 81 in theupper surface 825. The stator fixed portion 81 is press-fitted into thefixing member insertion portion 217 of the stator core 21.

At this time, the upper surface 825 comes into contact with the lowersurface of the stator core 21. Fixing between the stator fixed portion81 and the fixing member insertion portion 217 is not limited topress-fitting. For example, screwing or the like may be available.Methods enabling the first fixing member 8 to be firmly fixed while thestator fixed portion 81 is inserted into the fixing member insertionportion 217 to bring the upper surface 825 into contact with the lowersurface of the stator core 21 can be widely used.

Next, fixing between the circuit board 7 and the stator core 21 will bedescribed. Stator fixed portions 81 of two first fixing members 8 arepress-fitted into respective two fixing member insertion portions 217.At this time, the upper surface 825 of the large-diameter portion 821comes into contact with the lower surface of the stator core 21, and thefirst fixing member 8 is fixed to the stator core 21. This causes thestator core 21 and the first fixing member 8 to be electricallyconnected to each other. That is, this causes the stator core 21 and thefirst fixing member 8 to be identical in potential.

The fixing member insertion portion 217 is provided in the support rib215. That is, the stator fixed portion 81 is fixed radially inward ofthe teeth 212 of the stator core 21. This causes the circuit board 7 tobe disposed at a position overlapping the stator core 21 in the axialdirection, and causes the circuit board 7 and the stator core 21 to befixed to each other. Thus, the motor 100 can be prevented fromincreasing in size in the radial direction.

When the fixing member insertion portion 217 is provided in the supportrib 215, a force for pressing the first fixing member 8 is less likelyto act on the teeth 212. Thus, the teeth 212 can be prevented from beingdeformed or displaced, for example, so that the motor 100 can beprevented from deteriorating in rotational accuracy. When the supportrib 215 is provided with the fixing member insertion portion 217,turbulence in a magnetic circuit formed in the stator core 21 can bereduced. This enables a magnetic force to be effectively used, andenables increase in torque and power saving.

After that, the leg portion 820 is inserted into the board through-hole73 of the circuit board 7. At this time, the lower surface 824 of thelarge-diameter portion 821 comes into contact with the first wiringpattern 71. This causes the first wiring pattern 71 and the stator core21 to be electrically connected to each other using the first fixingmember 8 having conductivity, i.e., causes the first wiring pattern 71and the stator core 21 to be identical in potential. At this time, theupper surface of the circuit board 7 comes into contact with theinsulator protruding portion 221 as well. That is, the circuit board 7is held in the axial direction using the large-diameter portion 821 andthe insulator protruding portion 221.

Then, the caulking process is conducted by folding the caulked portion823, which is disposed in a lower end portion of the small-diameterportion 822, radially outward. This causes the circuit board 7 to besandwiched between the large-diameter portion 821 and the caulkedportion 823, and causes the board holding portion 82 to be held in thecircuit board 7. The caulked portion 823 comes into contact with thesecond wiring pattern 72 on the lower surface of the circuit board 7.The caulked portion 823 is integrated with the small-diameter portion822. Thus, the small-diameter portion 822 is electrically connected tothe second wiring pattern 72 using the caulked portion 823.

This causes the circuit board 7 to be held to the stator core 21 usingthe board holding portion 82. The first fixing member 8 havingconductivity allows the second wiring pattern 72 and the stator core 21to be electrically connected to each other. This causes the secondwiring pattern 72 and the stator core 21 to be identical in potential.

The circuit board 7 is made of metal or the like, and is held, forexample, by the stator core 21 having higher rigidity than the insulator22, using the first fixing member 8. This enables the circuit board 7 tobe fixed to the stator with high position accuracy and to be firmlyfixed thereto. Additionally, unnecessary stress is less likely to act onthe conducting wire of the coil 23, which is connected to the circuitboard 7, so that electric power can be accurately supplied to the coil23.

Fixing the circuit board 7 to the stator core 21 using the first fixingmember 8 enables the circuit board 7 and the stator core 21 to beelectrically conducted to each other. This causes the stator core 21 andthe circuit board 7 to be identical in potential, so that dischargebetween the stator core 21 and the circuit board 7 is less likely tooccur. Thus, electronic components mounted on the circuit board 7 can beprotected. For example, when the stator core 21 is grounded through thebracket 4 and the like, the circuit board 7 is grounded using the firstfixing member 8. This causes no ground wire to be connected to thecircuit board 7, so that wiring can be simplified.

More specifically, the small-diameter portion 822 is inserted into theboard through-hole 73 to bring the lower surface 824 of thelarge-diameter portion 821 into contact with the first wiring pattern 71on the circuit board 7. When the small-diameter portion 822 is broughtinto contact with the second wiring pattern 72 on the circuit board 7through the caulked portion 823, the stator core 21 is electricallyconnected to the first wiring pattern 71 and the second wiring pattern72 on both sides of the circuit board 7. That is, when the circuit board7 is held by the stator core 21 using the first fixing member 8, thecircuit board 7 can be held with high position accuracy, and the firstwiring pattern 71 and the second wiring pattern 72 formed on thecorresponding sides of the circuit board 7 can be easily electricallyconnected to the stator core 21. Additionally, the circuit board 7 canbe held in a simple process such as caulking, and the circuit board 7and the stator 2 can be brought into conduction through the first fixingmember 8.

Then, the position detection element 74 is mounted on the circuit board7 firmly fixed to the stator core 21 having high rigidity. This causes arelative position between the position detection element 74 and therotor 1 to be less likely to change. Thus, a position of the rotatingrotor 1 can be accurately detected.

The circuit board 7 is held on the lower surface of the stator core 21in the axial direction, but is not limited to this. For example, thecircuit board 7 may be held on the upper surface thereof in the axialdirection. Even in this case, the circuit board 7 is held using thefirst fixing member 8. The circuit board 7 may be held on a portionother than the upper surface and the lower surface.

FIG. 5 is an exploded perspective view of the rotor 1 as viewed frombelow in the axial direction. The rotor 1 includes the rotor hub 11, arotor holder 12, a rotor core 13, the magnet 14, and a spacer 15. Therotor 1 is rotatably supported by the shaft 3 using the bearing 6. Thatis, the rotor 1 is rotatable about a center axis.

As illustrated in FIGS. 1, 3, and 5, etc., the rotor holder 12 housesthe rotor core 13, the magnets 14, and the spacer 15 inside the rotorholder 12. The rotor holder 12 includes a holder lid portion 121 and aholder tubular portion 122. The holder lid portion 121 has an annularshape extending in a direction orthogonal to the center axis Cx. Theholder tubular portion 122 has a tubular shape extending axiallydownward from a radially outer edge of the holder lid portion 121. Thatis, the rotor holder 12 includes the holder lid portion 121 extending inthe radial direction, and the holder tubular portion 122 in a tubularshape extending from the radially outer edge of the holder lid portion121 to one side (downward) in the axial direction.

The holder lid portion 121 is provided at its center with a hubthrough-hole 120. Into the hub through-hole 120, a holder fixing portion111 of the rotor hub 11 is press-fitted and fixed. The fixing of theholder fixing portion 111 to the hub through-hole 120 is not limited topress fitting, and may be fixing such as bonding or welding. The holderfixing portion 111 may be fixed using a fixture, such as a screw. Fixingmethods capable of firmly fixing the rotor hub 11 and the rotor holder12 can be widely used.

The holder lid portion 121 includes a holder first surface 123, a holdersecond surface 124, and a connecting surface 125. The holder firstsurface 123 is a part of a lower surface of the holder lid portion 121in the axial direction, and is formed in an annular shape extendingradially inward from an inner surface of the holder tubular portion 122.The holder first surface 123 is a plane orthogonal to the center axisCx. The holder second surface 124 is a part of the lower surface of theholder lid portion 121 in the axial direction, and is formed in anannular shape disposed radially inward of the holder first surface 123.The holder second surface 124 is disposed axially above the holder firstsurface 123. The connecting surface 125 connects a radially inner end ofthe holder first surface 123 and a radially outer end of the holdersecond surface 124. The connecting surface 125 has a shape in which alongitudinal section taken along a plane including the center axis Cxhas a curved shape. However, the shape is not limited to this, andshapes connecting the radial inner end of the holder first surface 123and the radially outer end of the holder second surface 124 are widelyused.

That is, the holder lid portion 121 includes the holder first surface123 that extends radially inward from the inner surface of the holdertubular portion 122, the holder second surface 124 that extends radiallyand is disposed radially inward of the holder first surface 123 and onthe other side (upper side) in the axial direction, and the connectingsurface 125 connecting the radially inner end of the holder firstsurface 123 and the radially outer end of the holder second surface 124.

In the motor 100 of the present example embodiment, the holder lidportion 121 is formed by pushing the holder second surface 124 upward inthe axial direction. This causes a connecting portion between the holderlid portion 121 and the holder tubular portion 122 to be provided in itsouter surface with a recessed portion recessed inward. However, thestructure is not limited to this, and structures including the holderfirst surface 123, the holder second surface 124, and the connectingsurface 125 can be widely used.

The rotor holder 12 has a portion where the holder first surface 123 andthe holder second surface 124 are connected by the connecting surface125, the portion also serving as a reinforcing portion. That is,providing the holder first surface 123, the holder second surface 124,and the connecting surface 125, enables the rotor holder 12 to beincreased in rigidity.

The rotor hub 11 includes the holder fixing portion 111 and a bearingholding portion 112. The holder fixing portion 111 has a cylindricalshape extending axially downward from a body portion of the rotor hub11. The holder fixing portion 111 has an outer surface that ispress-fitted into the hub through-hole 120. This causes the rotor hub 11to be fixed to the rotor holder 12. The holder fixing portion 111 is notlimited to the above structure, and may be formed on an outer surface ofthe body portion, or may have a tubular shape extending axially upward.

The bearing holding portion 112 has a tubular shape extending axiallydownward from the body portion of the rotor hub 11. The bearing 6 isheld on an inner surface of the bearing holding portion 112. The bearingholding portion 112 is rotatably supported by the shaft 3 using thebearing 6. This causes the rotor 1 to be rotatably supported by theshaft 3 fixed to the bracket 4 via the bearing 6. Although in the motor100, the rotor 1 is rotatably supported by the shaft 3 via the bearing6, the present disclosure is not limited to this. For example, the motor100 may be configured such that the rotor 1 is fixed to the shaft 3, andthe shaft 3 is rotatably supported by a fixing part such as the bracket4.

Here, the bearing 6 will be described. The bearing 6 is a ball bearing.The bearing 6 includes an outer ring 61, an inner ring 62, and aplurality of balls 63. The outer ring 61 is fixed to the inner surfaceof the bearing holding portion 112. Although examples of a fixing methodinclude press fitting, the method is not limited to the press fitting.For example, a fixing method such as bonding may be used. The inner ring62 is fixed to the outer surface of the shaft 3. Although examples offixing of the inner ring 62 onto the shaft 3 also include press-fittingas with fixing of the outer ring 61, the fixing is not limited thereto.The plurality of balls 63 is disposed side by side in a radial clearancebetween the outer ring 61 and the inner ring 62 in the circumferentialdirection.

When at least two bearings 6 are provided at positions away from eachother in the axial direction, runout of the rotor with respect to theshaft 3 can be reduced. This enables improvement in rotational accuracyof the rotor 1. In the present example embodiment, the bearing 6 is aball bearing, but is not limited to this. For example, a fluid dynamicbearing may be used as the bearing. When a fluid dynamic bearing isused, at least two dynamic pressure generating grooves are formed inrespective portions away from each other in the axial direction. Theportions where the dynamic pressure generating grooves are formed serveas bearings.

The rotor core 13 annularly surrounds the center axis Cx, and is formedby stacking a plurality of rotor pieces each formed of anelectromagnetic steel plate or the like in the axial direction. Therotor core 13 is formed by stacking the plurality of rotor pieces in theaxial direction and fixing them by using a fixing method such ascaulking. This causes the rotor core 13 to be formed in a tubular shapeextending along the center axis Cx. The fixing of the rotor pieces isnot limited to caulking, and a fixing method such as bonding or weldingmay be used. The rotor core 13 is not limited to a stacked body, and maybe a molded body formed by solidifying magnetic powder such as ironpowder by sintering or the like.

As illustrated in FIG. 2 and the like, the rotor core 13 includes arotor core tubular portion 131 and a plurality of rotor core grooveportions 132. The rotor core tubular portion 131 has an annular shapeabout the center axis Cx. The rotor core tubular portion 131 has anouter surface that is in a cylindrical shape and is fixed inside theholder tubular portion 122. That is, the rotor core 13 is fixed insidethe holder tubular portion 122. The holder tubular portion 122 of therotor core 13 is fixed by press-fitting, for example. The fixing is notlimited to press-fitting, and the holder tubular portion 122 may befixed by bonding, welding, or the like. The holder fixing portion 111may be fixed using a fixture, such as a screw.

The rotor core groove portions 132 are each a recessed portion that isrecessed radially outward from an inner surface of the rotor coretubular portion 131. The rotor core groove portions 132 each extend froman upper end of the rotor core 13 in the axial direction to a lower endthereof. The number of the rotor core groove portions 132 is the same asthat of the magnets 14. The plurality of rotor core groove portions 132is disposed in the circumferential direction at intervals from thecorresponding adjacent rotor core groove portions 132. The plurality ofrotor core groove portions 132 is disposed at equal intervals in thecircumferential direction.

The rotor 1 includes 20 magnets 14 in the present example embodiment. Asillustrated in FIG. 5 and the like, the magnets 14 each have arectangular parallelepiped shape. Although the rotor 1 according to thepresent example embodiment has a plurality of magnets 14, the presentdisclosure is not limited to this. For example, there may be availablemagnets each of which is acquired by forming magnetic material into atubular shape, and is then alternately formed with a magnetic pole onits inner surface. That is, the rotor 1 includes one or more magnets 14.The magnets 14 are housed and held in the corresponding rotor coregroove portions 132. That is, the rotor 1 includes the rotor core 13that holds the magnets 14. The holding of the magnets 14 in thecorresponding rotor core groove portions 132 is performed by bonding,but is not limited to this. For example, the magnets 14 may be held bywelding, adhesion, or the like, or may be fixed using a fixture such asa screw. That is, the rotor 1 holds one or more magnets.

The magnets 14 are each disposed protruding radially inward from aninner surface of the rotor core 13. However, placement of the magnets 14is not limited to this, and inner surfaces of the magnets 14 and theinner surface of the rotor core 13 may be disposed on the samecylindrical surface in the radial direction. The inner surface of therotor core 13 may protrude radially inward from the magnets 14. Theinner surfaces of the magnets 14 in the radial direction face the stator2 in the radial direction. The magnets 14 each have the inner surface onwhich a different magnetic pole (N-pole or S-pole) is disposedalternately. When the magnet is formed in a tubular shape, the rotorcore 13 has a structure for holding an outer surface of the magnet. Tomore reliably fix the tubular magnet to the rotor core 13, a protrudingportion may be formed on one of the magnet and the rotor core, and arecessed portion into which the protruding portion is inserted may beformed on the other.

As illustrated in FIGS. 3 and 5, at least a magnet upper surface 140,which is an upper surface of the magnet 14 in the axial direction, is incontact with the spacer 15. That is, the rotor 1 includes the spacer 15that is in contact with the magnets 14 at least in the axial direction.Next, the spacer 15 will be described. As illustrated in FIGS. 1 and 5,the spacer 15 has an annular shape about the center axis Cx. That is,the spacer 15 has an annular shape. The spacer 15 includes a spacerfirst surface 151, a spacer second surface 152, a spacer inner surface153, and a spacer outer surface 154.

The spacer 15 has an annular shape. That is, the spacer outer surface154 is a cylindrical surface about the center axis Cx. Thus, the spacerouter surface 154 can support a rotor core upper surface 130 and themagnet upper surface 140 substantially uniformly throughout the entirecircumference in the circumferential direction. The spacer outer surface154 also comes into contact with the inner surface of the holder tubularportion 122 uniformly or substantially uniformly throughout the entirecircumference in the circumferential direction. This causes the spacer15 to be less likely to move in the holder tubular portion 122, andcauses the rotor core 13 and the magnets 14 to be easily attached.

The spacer first surface 151 is an upper surface of the spacer 15 in theaxial direction. The spacer first surface 151 comes into contact withthe holder first surface 123. The spacer second surface 152 is a lowersurface of the spacer 15 in the axial direction. The spacer secondsurface 152 comes into contact with the magnet upper surface 140 that isan upper surface of each of the magnets 14 in the axial direction. Thatis, the spacer second surface 152 comes into contact with a part of eachof the magnets 14. This causes the plurality of magnets 14 to be axiallypositioned when the magnet upper surface 140 comes into contact with thespacer 15.

This structure enables determining accurately and easily an axialposition of each of the plurality of magnets 14. Thus, magnetic forcesof the plurality of magnets 14 can be efficiently used. This enablesimprovement in torque without changing the motor 100 in size.Additionally, power consumption can be reduced as compared with a motor100 having constant torque. Further, positions of the plurality ofmagnets 14 can be adjusted at the same time. This enables work ofattaching the magnets 14 to be simplified.

The spacer inner surface 153 is disposed at a radially inner end of thespacer 15. That is, the spacer inner surface 153 is a radially inner endof the spacer 15. The spacer outer surface 154 is a cylindrical surface.The spacer outer surface 154 comes into contact with the inner surfaceof the holder tubular portion 122. The spacer outer surface 154 and theinner surface of the holder tubular portion 122 may be in contact witheach other to the extent that movement of the spacer 15 is restricted.That is, the spacer outer surface 154 and the inner surface of theholder tubular portion 122 are in contact with each other to the extentthat the spacer 15 does not move due to frictional force.

As illustrated in FIGS. 1 and 3, the rotor core upper surface 130, whichis an upper surface of the rotor core 13 in the axial direction, mayalso come into contact with the spacer second surface 152. That is, thespacer second surface 152 also comes into contact with a part of therotor core 13 in the axial direction.

When the spacer first surface 151 comes into contact with the holderfirst surface 123, and the spacer second surface 152 comes into contactwith the rotor core upper surface 130 and the magnet upper surface 140,the rotor core 13 and the magnet 14 are axially positioned with respectto the rotor holder 12.

As illustrated in FIG. 3, the connecting surface 125 of the holder lidportion 121 is disposed radially inward of the spacer inner surface 153.This causes the entire spacer first surface 151 to come into contactwith the holder first surface 123. Thus, the spacer 15 is stably incontact with the holder first surface 123, so that the rotor core 13 andthe magnets 14 are accurately fixed to the rotor holder 12. The term,“accurately fixed” means that the rotor core 13 and the magnets 14 arefixed to the rotor holder 12 such that the centers of the rotor core 13and the magnets 14 align with the center of the rotor holder 12 withoutbeing displaced.

The rotor core upper surface 130, which is the upper surface of therotor core 13 in the axial direction, and the magnet upper surface 140,which is the upper surface of each of the magnets 14 in the axialdirection, come into contact with the spacer 15 to be positioned in theaxial direction.

A rotor core lower surface 133, which is a lower surface of the rotorcore 13 in the axial direction, and a magnet lower surface 141, which isa lower surface of each of the magnets 14 in the axial direction, areboth positioned axially above a lower end of the holder tubular portion122 in the axial direction. That is, the rotor core 13 and each magnet14 have ends on one side in the axial direction that are located on theother side in the axial direction from an end of the holder tubularportion 122 on the one side in the axial direction.

This structure prevents the rotor core 13 and the magnets fromprotruding downward from the lower end of the holder tubular portion 122in the axial direction, so that the motor 100 can be reduced in heightin the axial direction. The rotor core 13 and the magnets 14 are housedinside the rotor holder 12 in the axial direction, so that magneticforces of the magnets 14 are less likely to be released to the outsideto enable the magnetic forces to be efficiently used. This improvestorque without changing the motor in size.

The spacer 15 may be made of a non-magnetic material. When the spacer 15is made of a non-magnetic material, magnetic flux leakage from themagnet upper surface 140 of each of the magnets 14 to the holder lidportion 121 is reduced. Thus, utilization efficiency of the magneticforce of each of the magnets 14 can be improved. This enablesimprovement in torque of the motor 100 or reduction in power consumptionthereof.

Next, a procedure for attaching the rotor core 13 and the magnets 14 tothe holder tubular portion 122 will be described. As illustrated in FIG.5, each of the magnets 14 is attached to the corresponding one of therotor core groove portions 132 of the rotor core 13. At this time, alower end of each of the magnets 14 in the axial direction protrudesfrom the rotor core 13.

In this state, the spacer 15 is inserted inside the rotor holder 12. Thespacer outer surface 154 of the spacer 15 and an inner surface of therotor holder 12 come into contact with each other, and the spacer 15 isheld inside the rotor holder 12 using a frictional force.

While a part of each of the magnets 14 is attached to the correspondingone of the rotor core groove portions 132, the rotor core 13 is disposedat a position allowing the rotor core 13 to be inserted from an openingat the lower end of the holder tubular portion 122 in the axialdirection. Then, for example, a plate-shaped jig (not illustrated) isbrought into contact with the lower surface of each of the magnets 14 inthe axial direction and then the jig is moved upward in the axialdirection. This causes each of the magnets 14 to move in the axialdirection inside the corresponding one of the rotor core groove portions132. The plurality of magnets 14 is simultaneously pressed by the jig.Thus, the plurality of magnets 14 is accurately adjusted in axialposition.

Although in the present example embodiment, the rotor core 13 and themagnets 14 are inserted from an opening at a lower end of the rotorholder 12 in the axial direction, the present disclosure is not limitedto this. For example, the rotor core 13 and the magnet 14 may beinserted into the rotor holder 12 having an opening at its upper end inthe axial direction. In this case, the magnets 14 can be attached to theinside of the rotor holder 12 by bringing the jig into contact with theupper surface of each of the magnets 14 in the axial direction andmoving the jig downward in the axial direction.

When the magnets 14 are pushed into the corresponding rotor core grooveportions 132 of the rotor core 13, the jig comes into contact with boththe lower surface of each of the magnets in the axial direction and thelower surface of the rotor core 13 in the axial direction. Furthermoving the jig axially upward causes the rotor core 13 with the magnets14 disposed in the corresponding rotor core groove portions 132 to bepress-fitted into the holder tubular portion 122. When the rotor coreupper surface 130 and the magnet upper surface 140 come into contactwith the spacer second surface 152, the press-fitting using the jig iscompleted. The rotor core 13 and the magnets 14 are positioned in theaxial direction by coming into contact with the spacer 15. Thus, evenwhen the rotor core 13 and the magnets 14 are pushed with theplate-shaped jig, axial positions of the rotor core 13 and the magnets14 can be accurately determined.

The magnets 14 are fixed to the corresponding rotor core groove portions132 by bonding. Before the magnets 14 are attached, an adhesive may beapplied to an inner surface of each of the rotor core groove portions132 or a portion of each of the magnets 14 that comes into contact withthe corresponding one of the rotor core groove portions 132.Alternatively, the rotor core 13 and the magnets 14 may be bonded toeach other after the rotor core groove portions 132 are press-fittedinto the holder tubular portion 122.

The adhesive may be disposed between radially outer surfaces of themagnets 14 and radially inner surfaces of the corresponding rotor coregroove portions 132. The adhesive also may be disposed between acircumferential end surface of each of the magnets 14 and an end surfaceof the corresponding one of the rotor core groove portions 132, facingthe circumferential end surface in the circumferential direction.Further, the adhesive may be disposed in both of the above-mentionedportions, i.e., all portions between surfaces of the magnets 14 andsurfaces of the corresponding rotor core groove portions 132, facingeach other. The placement positions of the adhesive are each an example,and the adhesive may be disposed at a place other than those positions.

When the rotor core 13 is press-fitted into the holder tubular portion122, the rotor core 13 receives a force inward in the radial direction.At this time, the magnets 14 attached to the corresponding rotor coregroove portions 132 are pressed in the circumferential direction andheld by the rotor core 13. The force of pressing the rotor core 13 maybe used as a part of a force for holding the magnets 14.

The method for fixing the rotor core 13 and the magnets 14 is anexample, and the method is not limited to this.

In the present example embodiment, the rotor core upper surface 130 andthe magnet upper surface 140 come into contact with the spacer secondsurface 152 of the spacer 15. When the rotor core 13 and the magnets 14are brought into contact with the spacer second surface 152, axialpositional accuracy of the rotor core 13 and the magnets 14 with respectto the rotor holder 12 can be easily increased.

Hereinafter, modifications of the motor according to the presentdisclosure will be described with reference to the drawings.

FIG. 6 is an enlarged sectional view of a fixed portion of a circuitboard 7A in a motor 100A of a first modification. The circuit board 7Aincludes a conductive portion 731 in a board through-hole 73A. Besidesthis, the circuit board 7A has the same configuration as the circuitboard 7. Thus, a portion of the motor 100A that is substantially thesame as that of the motor 100 is denoted by the same reference numeral,and duplicated detailed description will be eliminated.

As illustrated in FIG. 6, the conductive portion 731 is a conductivefilm. The conductive portion 731 is in close contact with an innersurface of the board through-hole 73A. Then, the conductive portion 731is electrically connected to a first wiring pattern 71 and a secondwiring pattern 72. More specifically, the conductive portion 731 is aconductive film similar to the first wiring pattern 71 and the secondwiring pattern 72, and electrically connects the first wiring pattern 71and the second wiring pattern 72.

When a small-diameter portion 822 is inserted into the boardthrough-hole 73A, a radially outer surface of the small-diameter portion822 comes into contact with the conductive portion 731. This causes thefirst fixing member 8 and the conductive portion 731 to be electricallyconnected to each other. This enables improvement in reliability of theelectrical connection between the first fixing member 8 and the firstwiring pattern 71 as well as the second wiring pattern 72.

FIG. 7 is an enlarged sectional view of a fixed portion of a circuitboard 7 in a motor 100B of a second modification. In the motor 100B, thecircuit board 7 is different in a leg portion 820B of a first fixingmember 8B. Besides this, the motor 100B has the same configuration asthe motor 100. Thus, a portion of the motor 100B that is substantiallythe same as that of the motor 100 is denoted by the same referencenumeral, and duplicated detailed description will be eliminated.

The leg portion 820B of the first fixing member 8B includes asmall-diameter portion 822B and a second fixing member 83. Thesmall-diameter portion 822B has a cylindrical columnar shape. Thesmall-diameter portion 822B has an outer diameter smaller than that of alarge-diameter portion 821. The small-diameter portion 822B is connectedto a lower surface 824. The small-diameter portion 822B includes a freeend having a shape that is less likely to deform. Then, thesmall-diameter portion 822B is inserted into a board through-hole 73 ofthe circuit board 7. The second fixing member 83 is then coupled to alower end portion of the leg portion 820B.

The second fixing member 83 is, for example, a push nut. Then, thesecond fixing member 83 is fixed to the lower end portion of thesmall-diameter portion 822B passing downward through the boardthrough-hole 73. The second fixing member 83 is fixed to thesmall-diameter portion 822B by being pushed from a leading end of thesmall-diameter portion 822B using a jig. This prevents thesmall-diameter portion 822B from being removed from the boardthrough-hole 73. At this time, the second fixing member 83 comes intocontact with a second wiring pattern 72. That is, the leg portion 820Bincludes the second fixing member 83 that has conductivity and iscoupled to the lower end portion of the small-diameter portion 822B.This causes the small-diameter portion 822B to be indirectly connectedto the second wiring pattern 72 using the second fixing member 83. Usingthe second fixing member 83 enables the small-diameter portion 822B tobe easily fixed to the circuit board 7.

Although in the present modification, the push nut is used as the secondfixing member 83, the present disclosure is not limited to this. Forexample, welding, soldering, or the like may be used. Additionally,forming a male thread on the small-diameter portion 822B and using a nutto be screwed into the male screw also can be used. The second fixingmember 83 can widely have a structure capable of not only firmly fixingthe first fixing member 8B and the circuit board 7, but also firmlyfixing the first fixing member 8B to the first wiring pattern 71 and thesecond wiring pattern 72.

FIG. 8 is an enlarged sectional view of a rotor 1C in a motor 100C of athird modification. The motor 100C has the same configuration as themotor 100, except that the rotor 1C includes a spacer 15C with astructure that is different from that of the rotor 1. Thus, a portion ofthe motor 100C that is substantially the same as that of the motor 100is denoted by the same reference numeral, and duplicated detaileddescription will be eliminated.

As illustrated in FIG. 8, a radially inner end of a rotor core 13 andradially inner ends of magnets 14 overlap a spacer second surface 152Cof the spacer 15C in the axial direction. This causes the entire rotorcore upper surface 130 of the rotor core 13 and the entire magnet uppersurface 140 of the magnets 14 to be in contact with the spacer secondsurface 152C. Thus, the rotor core 13 and the magnets 14 can be stablydisposed in a rotor holder 12. This enables stabilizing rotation of therotor 1.

FIG. 9 is a plan view of a spacer 16 used in a motor of a fourthmodification. As illustrated in FIG. 9, the spacer 16 has a radiallyouter edge in a shape in which a plurality of curved surface portions155 and a plurality of flat surface portions 156 are disposed in thecircumferential direction. Besides this portion, the spacer 16 has thesame structure as the spacer 15. Thus, a portion of the spacer 16 thatis substantially the same as that of the spacer 15 is denoted by thesame reference numeral, and duplicated detailed description of the sameportion is eliminated.

The curved surface portions 155 are each a part of a cylindricalcolumnar surface about a center axis. The flat surface portions 156 areeach formed by cutting an outer surface of the corresponding one of thecurved surface portions 155 into a flat shape in the circumferentialdirection. The flat surface portions 156 each constitute a chord asviewed in the axial direction. That is, the spacer 165 has the flatsurface portions 156 each acquired by cutting out at least a part of theradially outer surface of the spacer 165 in a flat shape.

As described above, the spacer 16 is housed inside the rotor holder 12.At this time, the curved surface portions 155 come into contact with aninner surface of a holder tubular portion 122. This causes frictionalforces to be generated between the inner surface of the holder tubularportion 122 and the curved surface portions 155. In contrast, the flatsurface portions 156 and the inner surface of the holder tubular portion122 do not come into contact with each other, so that no frictionalforce is generated. That is, adjusting the curved surface portions 155of the spacer 16 in size enables adjusting a frictional force betweenthe spacer 16 and the holder tubular portion 122. Allowing thefrictional force to be adjusted enables the spacer 16 to be easilyhoused inside the rotor holder 12, and enables restricting displacementof the spacer 16 in the axial direction. This enables improvement inworkability.

FIG. 10 is a view of a rotor 1D and a stator 2 of a motor 100D of afifth modification as viewed from below in the axial direction. FIG. 11is an enlarged longitudinal sectional view of the rotor 1D and thestator 2 of the motor 100D. FIG. 12 is an exploded perspective view ofthe rotor 1D as viewed from below in the axial direction. The motor 100Dis different in structure of a holder tubular portion 122D of a rotorholder 12D and a spacer 15D, and includes no rotor core. Besides this,the motor 100D has the same configuration as the motor 100. Thus, aportion of the motor 100D that is substantially the same as that of themotor 100 is denoted by the same reference numeral, and duplicateddetailed description of the same portion will be eliminated.

As illustrated in FIGS. 10 and 11, the motor 100D includes the rotorholder 12D with the holder tubular portion 122D to which a plurality ofmagnets 14 is attached. The spacer 15D includes a plurality of spacerprotrusions 157 extending axially downward from a spacer second surface152. That is, the spacer 15D includes the plurality of spacer protrudingportions 157 extending in the axial direction.

The holder tubular portion 122D includes an inner tubular portion 126and an outer tubular portion 127. The inner tubular portion 126 isconnected to an outer edge of a holder lid portion 121. The outertubular portion 127 has an inner surface that is in contact with anouter surface of the inner tubular portion 126. That is, the holdertubular portion 122D further includes the inner tubular portion 126 andthe outer tubular portion 127 having the inner surface that is incontact with the outer surface of the inner tubular portion 126. In thepresent modification, the outer tubular portion 127 is formed by foldingoutward an axially lower end portion of the inner tubular portion 126and bringing the folded portion into contact with the outer surface ofthe inner tubular portion 126. The folding direction is a radiallyoutward direction, but may be a radially inward direction.

The magnets 14 are directly attached to an inner surface of the holdertubular portion 122D. That is, in the motor 100D, a part of the holdertubular portion 122D serves as a rotor core. That is, at least a part ofthe holder tubular portion 122D includes the rotor core.

In the motor 100D, the spacer 15D is disposed with a spacer firstsurface 151 in contact with a holder first surface 123. At this time,the spacer protrusions 157 of the spacer 15D are disposed in contactwith the inner surface of the inner tubular portion 126. The spacerprotrusions 157 are provided as many as the magnets 14 and are disposedat equal intervals in the circumferential direction. That is, theplurality of spacer protruding portions 157 is disposed side by side inthe circumferential direction inside the inner surface of the holdertubular portion 122. The magnets 14 are disposed in contact with thecorresponding spacer protrusions 157 in the circumferential direction.That is, the magnets 14 are inserted between the corresponding pluralityof spacer protruding portions 157, and are fixed to the inner surface ofthe holder tubular portion 122D. That is, the spacer protrusions 157position the corresponding magnets 14 in the circumferential direction.

The outer tubular portion 127 is disposed with an upper end positionedabove magnet upper surface 140 of the magnets 14. The outer tubularportion 127 is disposed with a lower end positioned below magnet lowersurface 141 of the magnets 14. That is, the outer tubular portion 127has an end on the one side in the axial direction that is positioned onthe one side in the axial direction from ends of the magnets 14 on theone side in the axial direction. The outer tubular portion 127 has anend on the other side in the axial direction that is positioned on theother side in the axial direction from ends of the magnets 14 on theother side in the axial direction. When the outer tubular portion 127 isconfigured as described above, magnetic forces from the magnets 14 areless likely to be released radially outward.

The structure without a rotor core enables reducing the number ofcomponents of the motor 100D as compared with the motor 100. Thisfacilitates manufacturing of the motor 100D. Additionally, the motor100D also can be reduced in weight, and electric power required foroperating the motor 100D can be reduced.

FIG. 13 is a perspective view illustrating an example of a ceiling fan Ausing the motor 100 according to the present disclosure. Although themotor 100 is used in the ceiling fan A in FIG. 13, the motors 100A to100D of the modifications may be used.

The ceiling fan A includes the motor 100, a column 200, and blades 300.The column 200 is disposed along a center axis Cx extending vertically.The column 200 is, for example, a tubular member made of metal. Thecolumn 200 is provided inside with lead wires (not illustrated)connected to a circuit board 7. The column 200 may be made of a materialother than metal, such as ceramic.

The column 200 is fixed to a ceiling (not illustrated) of a living room.The motor 100 is attached to a lower end of the column 200 in the axialdirection. In the ceiling fan A, the motor 100 illustrated in FIG. 1 isattached to the column 200 while being vertically inverted. That is, abracket 4 is fixed to the lower end of the column 200 in the axialdirection.

Then, the blades 300 are attached to a holder lid portion 121 of a rotorholder 12. The blades 300 each have a shape extending in the axialdirection as it extends in the circumferential direction. When the motor100 rotates, the blades 300 rotate in the circumferential direction.When the blades 300 rotate, an airflow is generated in a direction alonga center axis of the column 200.

The motor according to the present disclosure can be widely used as apower source not only for a blower apparatus but also for rotating arotor.

Although the example embodiments of the present disclosure have beendescribed above, the present disclosure is not limited to the contentsdescribed above. The example embodiments of the present disclosure canbe modified in various ways without departing from the spirit of thedisclosure.

The motor of the present disclosure can be used, for example, as a driveunit that drives a blower apparatus such as a circulator. Besides ablower apparatus, the motor of the present disclosure can be used as apower source for supplying a rotational force to the outside.

Features of the above-described preferred example embodiments and themodifications thereof may be combined appropriately as long as noconflict arises.

While example embodiments of the present disclosure have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present disclosure. The scope of the presentdisclosure, therefore, is to be determined solely by the followingclaims.

What is claimed is:
 1. A motor comprising: a rotor rotatable about acenter axis; and a stator radially opposing the rotor; wherein the rotorincludes: one or more magnets; a rotor core holding the one or moremagnets; a spacer that is in contact with at least the one or moremagnets in an axial direction; and a rotor holder that houses the one ormore magnets, the rotor core, and the spacer inside the rotor holder;the rotor holder includes: a holder lid portion that extends in a radialdirection; and a holder tubular portion in a tubular shape extending toone side in the axial direction from a radially outer edge of the holderlid portion; the holder lid portion includes: a holder first surfacethat extends radially inward from an inner surface of the holder tubularportion; a holder second surface that extends radially and is radiallyinward of the holder first surface and on another side in the axialdirection; and a connecting surface connecting a radially inner end ofthe holder first surface and a radially outer end of the holder secondsurface; and the spacer includes: a spacer first surface in contact withthe holder first surface, the spacer first surface being an uppersurface of the spacer and the holder first surface being a lower surfaceof the rotor holder; and a spacer second surface in contact with aportion of each of the one or more magnets, the spacer second surfacebeing a lower surface of the spacer; the spacer is defined by a singlemonolithic element; and all portions of the spacer are below the rotorholder such that no portion of the spacer is located axially higher thanany portion of the rotor holder.
 2. The motor according to claim 1,wherein the spacer second surface is in contact with a portion of therotor core in the axial direction.
 3. The motor according to claim 1,wherein the rotor core and each of the one or more magnets include endson one side in the axial direction that are located on another side inthe axial direction from an end of the holder tubular portion on the oneside in the axial direction.
 4. The motor according to claim 1, whereinthe rotor core and a radially inner end of each of the one or moremagnets overlap the spacer second surface in the axial direction.
 5. Themotor according to claim 1, wherein the holder tubular portion at leastpartly includes the rotor core; the spacer includes a plurality ofspacer protruding portions extending in the axial direction; theplurality of spacer protruding portions is inside the inner surface ofthe holder tubular portion and is arranged side by side in acircumferential direction; and the one or more magnets are insertedbetween the corresponding plurality of spacer protruding portions andare fixed to the inner surface of the holder tubular portion.
 6. Themotor according to claim 5, wherein the holder tubular portion furtherincludes an inner tubular portion and an outer tubular portion includingan inner surface that is in contact with an outer surface of the innertubular portion; the outer tubular portion includes an end on one sidein the axial direction that is positioned on the one side in the axialdirection from an end of each of the one or more magnets on the one sidein the axial direction; and the outer tubular portion includes an end onthe another side in the axial direction that is positioned on theanother side in the axial direction from an end of each of the one ormore magnets on the another side in the axial direction.
 7. The motoraccording to claim 1, wherein the spacer has an annular shape.
 8. Themotor according to claim 1, wherein the spacer is a non-magnetic body.9. The motor according to claim 1, wherein the radially inner surface ofthe magnet is closer to a radially outer surface of the stator than aradially inner surface of the spacer is.
 10. A motor comprising: a rotorrotatable about a center axis; and a stator radially opposing the rotor;wherein the rotor includes: one or more magnets; a rotor core holdingthe one or more magnets; a spacer that is in contact with at least theone or more magnets in an axial direction; a rotor holder that housesthe one or more magnets, the rotor core, and the spacer inside the rotorholder; the rotor holder includes: a holder lid portion that extends ina radial direction; and a holder tubular portion in a tubular shapeextending to one side in the axial direction from a radially outer edgeof the holder lid portion; the holder lid portion includes: a holderfirst surface that extends radially inward from an inner surface of theholder tubular portion; a holder second surface that extends radiallyand is radially inward of the holder first surface and on another sidein the axial direction; and a connecting surface connecting a radiallyinner end of the holder first surface and a radian outer end of theholder second surface; the spacer includes: a spacer first surface incontact with the holder first surface; and a spacer second surface incontact with a portion of each of the one or more magnets; and theconnecting surface is radially inward of a radially inner end of thespacer.
 11. A motor comprising: a rotor rotatable about a center axis;and a stator radially opposing the rotor; wherein the rotor includes:one or more magnets; a rotor core holding the one or more magnets; aspacer that is in contact with at least the one or more magnets in anaxial direction; and a rotor holder that houses the one or more magnets,the rotor core, and the spacer inside the rotor holder; the rotor holderincludes: a holder lid portion that extends in a radial direction; and aholder tubular portion in a tubular shape extending to one side in theaxial direction from a radially outer edge of the holder lid portion;the holder lid portion includes: a holder first surface that extendsradially inward an inner surface of the holder tubular portion; a holdersecond surface that extends radially and is radially inward of theholder first surface and on another side in the axial direction; and aconnecting surface connecting a radially inner end of the holder firstsurface and a radially outer end of the holder second surface; thespacer includes: a spacer first surface in contact with the holder firstsurface; and a spacer second surface in contact with a portion of eachof the one or more magnets; the spacer has an annular shape; and thespacer includes a flat surface portion defined by a cut out of at leasta portion of a radially outer surface of the spacer with a flat shape.